Spring peening



June 25, 1963 c. P. CROFT 3,094,768

SPRING PEENING Filed March 29, 1961 :VQLM

IN VENTOR Ckw'ZcsP 6' 7 ft BY g mag ATTORNEYS United States Patent3,094,768 SPRING PEENING Charles P. Croft, Hagerstown, Md., assignor toPangborn Corporation, Hagerstown, Md., a corporation of Maryland FiledMar. 29, 1961, Ser. No. 99,107 4 Claims. (Cl. 2990) The presentinvention relates to the peening of springs so as to increase theirresistance to fatigue cracking and the like.

It is generally desired to peen springs of the elongated or leaf type sothat the section of the spring which is under tension during use, isunder tension when it is peened.

Among the objects of the present invention is the provision of a verysimple process and apparatus for carrying out the above peening undertension. This as well as other objects of the present invention will bemore clearly understood from the following description of several of itsexemplifications, reference being made to the accompanying drawingswherein:

FIG. 1 is a plan view, somewhat diagrammatic, of one form of apparatusin accordance with the present invention; and

FIG. 2 is a similar view of a difierent form of the above apparatus.

According to the present invention springs of the above type are peenedon a continuous basis by mounting a succession of the springs inunstressed condition on a conveyor having a series of securing members,fitting the securing portions of the respective springs on thesuccessive securing members, actuating the conveyor to carry the securedsprings through a peening zone, said zone having deflector means thatengages the successive springs and deflects them to place under tensionthose portions that are under tension when the springs are in use, sothat the springs are automatically peened under tension.

The conveyor can be a rotary one or an elongated linear one, and canhave a series of pins over which loops on the ends of the springs areplaced.

Referring now to the drawings, the construction of FIG. 1 is builtaround a table journalled for rotation on a vertical post 12 andcarrying on its upper face a series of fixed pins 14 and yieldably heldpins 16. In the form shown the yieldability of pins 16 is provided byhaving these pins mounted on arms 18 which are in turn pivoted as at 20to the table. The arms 18 can then be resiliently held in a positionthat brings their pins 16 to the desired location with respect to pins14 so that both pins will receive the end loops 21, 22 of a leaf spring24.

Immediately above the table and in the plane of the pins 14, 16 thereare shown two deflecting rollers 31, 32, each journalled on a bearingsupport 34 secured from above. The deflecting rollers 31, 33 are locatedabove one side of the table in a zone that is sealed off by a flexiblecurtain 35 from the other side of the table as in the manner shown inU.S. Patent 2,719,387 granted October 4, 1955. The side of the curtainin which the deflecting rollers are located is also provided withpeening equipment shown in the form of blasting wheels 38, 40 arrangedto project a stream of peening shot against the outwardly facingsurfaces of the springs 24 as they are carried through the blasting zonein the direction indicated by the arrow 42. As the springs come intoposition near the blasting wheels, the deflecting rollers are arrangedto flex the springs as illustrated, so that the outer faces of thesprings are under tension as they are blasted.

The apparatus of FIG. 1 is used by mounting the 3,094,768 Patented June25, 1963 "ice springs on the spring-receiving pins as these pins arecarried past a loading zone indicated by the legend Loa These springscan be exceedingly stiff and therefore very ditficult to flex, yet thesimple slipping of the springs over the receiving pins is all that isneeded at the loading zone. As the springs are carried around by therotation of the table they successively come into engagement withdeflecting roll 31, which causes the springs to be deflected as theycontinue in their rotary path. While in deflected condition they alsomove through the blasting area of wheel 38. The springs then move awayfrom deflecting roller 31 and are subjected to another peening treatmentby a similar coaction with deflecting roller 32 and blasting wheel 40.After the second peening treatment the springs are carried away fromdeflecting roller 32 and to the unloading position shown by the legendUnload where they can be easily lifted off their mounting pins.

The two peening treatments can be arranged with the blasting directed atthe springs from different perspectives so as to assure adequate peeningat all desired portions of the springs. Additional peening can also bearranged for other surfaces of the spring and these other treatments canbe carried out at locations where they operate on the spring while inundeflected condition, as for example in the area where the springs aredisengaged from both deflector rollers. In this way the supplementalsurfaces are not under compression when the supplemental peening iscarried out.

Alternatively only a single peening action can be used by eliminatingthe deflecting roller 32 and the blasting wheel 40. On the other hand,where two or more blasting wheels are used, at least one can be locatedsomewhat above the plane of the pins and tilted downwardly to moreeffectively treat the upper edges of the springs and one or more otherwheels can be in the opposing position tilted upwardly to better reachthe bottom edges of the springs. For access to these lower edges, thepins 14, 16 can be arranged to hold the springs spaced a few inchesabove the top of the table, or if desired, the table rim can bescalloped or notched so as to expose these lower edges.

The construction of FIG. 2 is arranged to effect an operation similar tothat of FIG. 1, using a linear conveyor 100. This conveyor need benothing more than a pair of endless chains 101, 10 2 parallel to eachother and looped around sprockets 104, 106 and carrying a series ofcross-slats 108 and 110. The slats 108 are provided with fixed pins 114,and the slats 110 with yieldable pins 116.

Only a single peening treatment is shown in FIG. 2 using a combinationof a blasting wheel '138 and an opposing deflecting roller 131 held :ona fixed bearing 134. Although such fixed deflecting roller will give thedesired deflection without any further deflection means, the apparatusof FIG. 2 also includes a stationary cam 133 that coacts with rollers135 carried by the pins 116 at a level below the springs. Thecombination of the deflecting cam 133 and the deflecting roller 131 asthe springs are carried in the direction of the arrow 142, provideswhatever spring flexing is needed.

With the linear conveyor as in FIG. 2, the springs can be arranged toautomatically unload as by merely having the pins 114, 116 small enoughto fit very loosely in the spring loops. The movement of the chainsaround the sprockets 106 will then cause the pins to be withdrawn fromthe loops so that the springs will automatically drop from the conveyor.

In the constructions of FIG. 1 or FIG 2, the pins 16 and 116 need not bearranged to receive a spring loop. Instead the corresponding end of thespring can merely be placed on the side of these pins which faces thedefleeting rollers. With such an arrangement the tabletype conveyor canhave the pins 16 fixed rather than yieldable since these pins would nothave to move to permit the spring to be flexed. The small amount offriction in the movement in the flexing spring along these pins is noproblem, but if desired these pins can he 'rotatably held so that theyrotate around their own longitudinal axes. Similarly the pins 116 of thelinear conveyor'can also be fixed where no deflecting cam is used.

The use of only one spring loop formounting simplifies the loading andunloading. Where such fixed pins are used and one partially obstructssome of the surface that is to be peened, a multiple peening treatmentcan be used, as in FIG. '1, with'diiferent degrees of flexing at eachpeening site so that the surface obstructed in one peening operation isfully treated in another.

Instead of using pins, the springs can be held by any other kind -ofmechanism such as receiving pockets or gripping clamps-or the like.Receiving pockets need be nothing more than short metal angles facingeach other and separated by a distance suflicient to allow the spring toextend between them, and arranged to permit the received spring to flex.Such pockets or clamps can be arranged to be movable-if desired, so asto permit them to follow the flexing of the spring. Such -.arrangementsare eflective for treating leaf springs that have no loops, andthe-clamps can be used on both ends-of such leaf springs or the clamp atone end can cooperate with a pin or other support for the otherend.

The movement of the rotary conveyor of FIG. 1, or the linear conveyor ofFIG. 2 can either be continuous or it can be intermittent. Also theoperation of the peening equipment such as the throwing Wheels of theseFIG- URES, can also be either continuousor they can be cut E except atsuch times when the flexed surfaces are in the proper position forreceiving the peening treatment.

The conveyors of the present invent-ion can also be used to tilt thesprings as they pass through the peening zones. By way of example, themounting pins 14 and the pivots 20 for the mounting pins 16 can beextended through generally radial slots in the table so as to projectbelow the table, and can be secured to the table top by alignedhorizontal pivots. At the peening zones tilting cams ean be providedbeneath the table to engage the lower projecting ends of the pins 14 andpivots -20 to tilt them in one-or-more steps or in acontinuous manner asthe peening takes place. This would provide better peening actionwhereonly a single peening apparatus is used.

The peening can be carried out by mechanisms other than blasting wheelsif desired. Thus a set of pneumatic hammers can be provided in thepeening zone and posipracticed otherwise than as specifically described.

What is claimed:

1. A spring peening apparatus comprising a conveyor, securing means onthe conveyor for holding a spring in unstressed condition,.deflector'means positioned adjacent the-path of travel of said conveyorfor stressing the spring as it is moved into contactwith said deflectingmeans by the conveyor, peening means positioned adjacent the path oftravel of-said conveyor and also said deflecting means for projectingpeening particles againstsaid spring as it is deflected, and meansfor-moving said conveyor to, past, and beyondsaid deflector means.

2. The combination of claim 1 in which the securing -means includes apair of spacedipins over which the loops of an individual spring lit,and one of the .pins is yieldably mounted so as to permit thespringlength to change when it is deflected.

3. The apparatus of claim 2 wherein the conveyor is rotarywithrespect'tothe deflector means.

4. The apparatus 0f claim 2 wherein the conveyor is linearly movable ina straight path past said deflector means.

References Cited in the file of this patent UNITED STATES PATENTS2,252,823 Wallace Aug. 19, 1941 2,338,591 Learmonth Jan. 4, 19442,608,752 "Schilling Sept. 2, '1952

1. A SPRING PEENING APPARATUS COMPRISING A CONVEYOR, SECURING MEANS ON THE CONVEYOR FOR HOLDING A SPRING IN UNSTRESSED CONDITION, DEFLECTOR MEANS POSITIONED ADJACENT THE PATH OF TRAVEL OF SAID CONVEYOR FOR STRESSING THE SPRING AS IT IS MOVED INTO CONTACT WITH SAID DEFLECTING MEANS BY THE CONVEYOR, PEENING MEANS POSITIONED ADJACENT THE PATH OF TRAVEL OF SAID CONVEYOR AND ALSO SAID DEFLECTING MEANS FOR PROJECTING PEENING PARTICLES AGAINST SAID SPRING AS IT IS DEFLECTED, AND MEANS FOR MOVING SAID CONVEYOR TO, PAST, AND BEYOND SAID DEFLECTOR MEANS. 